Migratory songbirds have unique life-histories in that they return to the same breeding territories year after year. In the neotropical migrant Black-capped Vireo (Vireo atricapilla), it has been observed that, in spite of their high vagility, substantial population differentiation is present, indicating a low degree of movement between populations. Among birds in general, and songbirds specifically, a variety of social structures have been recorded, and it is suspected that social organization may influence how frequently and how far individuals disperse. The objective of our study was to obtain a high resolution understanding of social organization within a population of the endangered Black-capped Vireo using microsatellite markers. Using this data and continued sampling of the population, we hope to track the extent of movements of individual genotypes.Individuals were captured, banded and sampled for blood at Kerr Wildlife Management Area. Approximately 20% of all breeding males in the population were sampled and 14 microsatellite loci available for this species are being genotyped.

Results/Conclusions

Preliminary results indicate high relatedness values among sampled individuals. Additionally, correlations of genetic distance and geographic distance show that related individuals may occur in close aggregations, indicating social organization and it may act as a barrier to random dispersal of individuals. Completion of genetic analyses will yield additional details on the organization of pedigrees in this population. Further sampling of the same population is planned in order to obtain an understanding of the temporal aspect of this social organization and to resolve dispersal events into the population.